Method to upgrade hydrocarbon mixtures

ABSTRACT

A method of upgrading hydrocarbon mixtures without the need of additives, catalysts or heating using ultrasonic cavitation. Ultrasonic energy is provided at a rate sufficient to induce cavitation in the hydrocarbon mixture. The high temperatures and high pressures resulting from cavitation cause cracking of a portion of the hydrocarbons in the mixture thereby creating lighter hydrocarbons in the diesel range or lighter for recovery via more traditional separation technologies, such as distillation. The resulting upgraded petroleum product exhibits lower distillation curves and decreased pollution causing components. Further, a wide variety of feedstocks can be treated according to the method of this invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. application Ser. No.60/299,107, filed Jun. 18, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention This invention relates to petroleummixtures, and, more specifically, to hydrocarbon mixtures and acavitational method for separating various hydrocarbon fractions fromthe same.

[0003] 2. Related Art

[0004] The commercial and household products that are derived from crudeoil are almost too numerous to mention. Petroleum products are used inthe manufacture of goods utilized in residential and commercialconstruction, automobiles, fibers for clothing, holiday decorations,food processing and packaging, medical devices, and the synthesis ofpharmaceuticals. The route from crude oil to sweaters, CD's, carbumpers, roofing shingles, etc., is a long one involving refining andreforming. The products which can be derived from an average barrel ofcrude oil, which contains 42 gallons, include gasoline to power ourvehicles; kerosene used as a jet fuel and used around the world forcooking and space heating; liquefied petroleum gas (LPG) used as fueland as an intermediate material in the manufacture of petrochemicals;diesel fuels and domestic heating oils; residual fuels or combinationsof residual and distillate fuels for heating and processing; coke usedas briquets; asphalt used for roads and roofing materials; solvents suchas benzene, toluene, and xylene; petrochemical feedstocks used in theproduction of plastics, synthetic fibers, synthetic rubbers, and otherproducts; and lubricating oil base stocks such as motor oils, industrialgreases, lubricants, and cutting oils.

[0005] High-grade crudes which directly produce large amounts ofgasoline have the most commercial value. Those which need considerablereforming to produce significant amounts of gasoline or contain largerthan usual amounts of metals such as vanadium (which poisons or shortensthe life of the catalysts used in reforming) have the lowest dollarvalue. The average crude, after refining, typically yields anapproximate product mixture shown below in Table 1. TABLE 1 Averageproduct mixture of refined crude oil. Refinery Product Hydrocarbon RangePercent Gasoline  C₅-C₁₀ 27 Kerosene C₁₁-C₁₈ 15 Diesel C₁₄-C₁₉ 11 HeavyGas Oil C₁₂-C₂₅ 10 Lubricating Oil C₂₀-C₄₀ 20 Residuum >C₄₀ 17

[0006] While there are direct markets for the lighter fuels (gasoline,kerosene, and diesel), in order to be profitable the other components ofthe crude oil, especially the gas oil and residuum, need to be convertedinto marketable products. This is the role of catalytic cracking.Further, about 70% of crude oil used in the United States undergoes sometype of conversion process. An overview of common petroleum refiningprocesses is shown below in Table 2. TABLE 2 Overview of PetroleumRefining Processes Process name Action Method Purpose Feedstock(s)Product(s) Fractionation Processes Atmospheric Separation ThermalSeparate fractions Desalted crude oil Gas, gas oil, distillationdistillate, residual Vacuum Separation Thermal Separate w/o AtmosphericGas oil, lube distillation cracking tower residual stock, residualConversion Processes - Decomposition Catalytic Alteration CatalyticUpgrade gasoline Gas oil, coke Gasoline, cracking distillatepetrochemical feedstock Coking Polymerize Thermal Convert vacuumResidual, heavy Naptha, gas oil, residuals oil, tar coke Hydro-Hydrogenate Catalytic Covert to oil, Gas oil, cracked Ligher, higher-cracking lighter HCs residual quality products Hydrogen DecomposeThermal/ Produce hydrogen Desulfurized gas, Hydrogen, CO, steam cat. O₂,steam CO₂ reforming Steam Decompose Thermal Crack large Atm. tower heavyCracked naptha, cracking molecules fuel/distillate coke, residualVisbreaking Decompose Thermal Reduce viscosity Atmospheric Distillate,tar tower residual Conversion Processes - Unification AlkylationCombining Catalytic Unite olefins & Tower isobutane/ Iso-octane amp;isoparaffins crckr olefin (alkylate) Grease com- Combining ThermalCombine soaps & Lube oil; fatty Lubricating pounding amp; oils acid;alky metal grease Poly- Polymerize Catalytic Unite 2 or more Crackerolefms High-octane merization olefins naptha, petrochemical stocksConversion Processes - Alteration or Re-arrangement CatalyitcAlteration/de Catalytic Upgrade low- Coker/hydro- High-octane reforming-hydration octane cracker reformate

[0007] Despite the various processes for converting petroleum, theindustry still suffers from an inability to efficiently convert heavyhydrocarbon fuels into lighter, more valuable hydrocarbons. Currentmethods of catalytic cracking of heavy hydrocarbon fuels are expensive,inefficient, and require large amounts of capital investment. Currentmethods also produce less than desirable results because cracking israndom and unpredictable. Heavy hydrocarbons containing highconcentrations of trace metals, such as vanadium, cause fouling of mostcommon catalysts so as to preclude catalytic cracking. Further, manyvacuum gas oils contain lighter fractions which, when catalyticallycracked, produce excess amounts of gases and undesirable by-products.

[0008] The petroleum industry has explored many avenues for reducingthese problems. Among these avenues is the use of sonic and ultrasonicenergy in a variety of applications. Most frequently ultrasonic energyis used in conjunction with various carrier agents, such as surfactantsand other emulsifying agents, to cause scission of carbon-carbon bondsin various petroleum mixtures. Most methods involve the use of anemulsifying agent, catalyst, or a combination of the two among a varietyof processing methods.

[0009] Crude oil is comprised of hydrocarbon fractions of varying chainlengths, as seen in Table 1. The longer chain lengths have progressivelyhigher boiling points, and therefore the varying chain lengths can beseparated out by distillation. In a typical oil refinery, crude oil isprogressively heated and the constituent components are largelyvaporized according to their boiling points corresponding to thepressure existing in the column at that point. The various componentsmay then be drawn from the column at points of differing temperaturesand pressures. The heavier fractions recovered, such as heavylubricating oils and residuums, generally have significantly lesscommercial value than the lighter fractions.

[0010] Other methods involve the use of ultrasound on intentionallycreated oil-in-aqueous phase emulsions in the presence of a catalyst.These types of methods crack heavier hydrocarbons to produce lightermore valuable products with the added expense of creating andcontrolling the emulsion composition, often complex additives, and acatalyst.

[0011] Therefore, there remains a need in the art for an efficient andcost-effective method of upgrading hydrocarbon mixtures that does notrequire additives such as water or other catalysts, does not require theformation of an emulsion, and does not require heating the hydrocarbonmixtures prior to or during the upgrading process.

SUMMARY OF THE INVENTION

[0012] This invention provides an improved method for upgrading heavyhydrocarbon fractions. Treatment using the method of the presentinvention can improve the separability of various hydrocarbon fractionsfrom crude oils and other hydrocarbon mixtures. By treating hydrocarbonmixtures with energy sufficient to cause cracking of the covalentcarbon-carbon bonds this invention also has utility for the productionof more valuable hydrocarbon products from what were previouslyconsidered very low value heavy hydrocarbon mixtures. As such, acompletely new source of feedstock for the production of valuablepetroleum products can be made available for use by petroleum refinersto expand the range of feedstock currently available.

[0013] The method of the present invention involves upgrading ahydrocarbon mixture. The hydrocarbon mixture is treated withcavitational energy sufficient to cause cracking. The various resultinghydrocarbon fractions may then be separated using any number ofseparation technologies, most often distillation.

[0014] In another aspect of the present invention the cavitationalenergy may be provided using ultrasonic, electromagnetic, propeller,impeller, venturi methods, or combinations thereof.

[0015] An advantage of the method of the present invention is that awide variety of hydrocarbon mixtures can be used as feedstock.Non-limiting examples include crude oil, atmospheric tower refiningbottoms, used motor oil, vacuum gas oils, refining residuums, fuel oil,vacuum tower bottoms, residual fuel oils and mixtures of thesefeedstocks.

[0016] In another more detailed aspect of the present invention thehydrocarbon mixture further includes components containing nitrogen,chlorine, sulfur or oxygen.

[0017] Still another more detailed aspect of the present invention is totreat heavy hydrocarbon mixtures containing predominantly hydrocarbonshaving a boiling point greater than that of diesel.

[0018] In another more detailed aspect of the present invention thehydrocarbon mixture is treated at a temperature between about 300° F.and 500° F.

[0019] In yet another more detailed aspect of the present invention thehydrocarbon mixture is treated in the absence of a substantial aqueousphase or additives.

[0020] In one more detailed embodiment of the invention a cup-shapedflow tube is used to direct flow of the hydrocarbon mixture toward theultrasonic energy source and accelerate flow to the turbulent flowregime.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described with reference to theaccompanying drawings. In the drawings, like reference numbers indicateidentical or functionally similar elements. Additionally, the left-mostdigit(s) of a reference number identifies the drawing in which thereference number first appears.

[0022]FIG. 1 is a block diagram showing the method steps of the processof the present invention for applying cavitational energy to treathydrocarbon mixtures;

[0023]FIG. 2 is a schematic diagram showing a system for treatinghydrocarbon mixtures according to one embodiment of the presentinvention; and

[0024]FIG. 3 is a schematic diagram showing one possible flowconfiguration past an ultrasonic energy source of the system shown inFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0025] A. Definitions

[0026] In conjunction with the disclosure herein, the following termswill be used as defined, unless otherwise specified or made clear in thecontext used.

[0027] As used herein, “hydrocarbon fuel”, “hydrocarbon mixture” and“hydrocarbon product” are used interchangeably and refer to anypetroleum or hydrocarbon mixture such as crude oil, used motor oil,vacuum gas oils, refining residuums, cat cracker bottoms, fuel oil,vacuum tower bottoms, atmospheric tower refining bottoms, residual fueloils and mixtures thereof. Frequently, the hydrocarbon product haspreviously undergone more traditional separation and/or distillationprocesses or is a residual product of other processes. Further, manyhydrocarbon mixtures of interest also contain complex mixtures ofheterocyclic and heteroatom hydrocarbon compounds, aromatics, cyclichydrocarbons, trace elements and hydrocarbons having non-carbonconstituent groups which include but are not limited to sulfur, oxygen,nitrogen and various combinations of these. Examples of such compoundsinclude but are not limited to quinolines, pyrrols, cresols, alcoholsand phenols.

[0028] As used herein, “heavy hydrocarbon mixture” refers to hydrocarboncontaining mixtures containing predominantly components having a boilingpoint above that of the diesel range.

[0029] As used herein, “hydrocarbon fraction” is intended to refergenerally to a portion of a hydrocarbon mixture which, if isolated,exhibits a bounded range of boiling points at a given pressure distinctfrom the remainder of the hydrocarbon mixture or other existinghydrocarbon fractions. This definition includes both hydrocarbonfractions which may not actually distill prior to treatment according tothe present invention and those fractions which distill withouttreatment.

[0030] As used herein, “cavitation” refers to the result of stressesinduced in a liquid by the passing of a sound wave through the liquid. Asound wave consists of compression and decompression/rarefaction cycles.These waves may be produced by a variety of methods such as when analternating current voltage is applied to a crystal, the crystal expandsand contracts in phase with the electric field according to thepiezoelectric effect, or expansion and contraction of amagnetorestrictive alloy. If the pressure during the decompression cycleis low enough, localized areas of vaporized liquid form to leave smallbubbles based on the uneven ultrasonic excitation of molecules. Thesecavitation bubbles (similar to those seen arising from the action of aboat propeller on water) are at the heart of ultrasonic cavitation orsonochemistry systems. This series of sound wave cycles causes thebubbles to grow during a decompression phase, and contract or implodeduring a compression phase. Thus the size, and resulting temperaturesand pressures upon implosion, of the bubbles is related to the frequencyand intensity of the sound waves. Each one of these imploding bubblescan therefore be seen as a microreactor, with temperatures reaching overan estimated 5000° C., and pressures of over several hundredatmospheres. Cavitation is therefore the production of cavities orbubbles in a fluid using ultrasound followed by an implosion of thecavity.

[0031] As used herein, “cavitational energy” refers to energy which issufficient to cause cavitation to occur in a liquid. The cavitationalenergy may be provided using various methods known to those skilled inthe art.

[0032] As used herein, “upgrading” refers to any process by which thequality or properties of the hydrocarbon mixture is improved and ismeant to include both physical and chemical changes to composition.Further, upgrading of hydrocarbon mixtures according to the presentinvention will involve the chemical change of cracking of a portion ofthe hydrocarbons into shorter chain lengths.

[0033] As used herein, the “pour point” of a fluid is the lowesttemperature at which a fluid is observed to flow, when cooled underconditions prescribed by test method ASTM D 97. The pour point is 3° C.(5° F.) above the temperature at which the fluid in a test vessel showsno movement when the container is held horizontally for five seconds.

[0034] B. Method of Separating Fractions from a Hydrocarbon Mixture

[0035] Referring now to FIG. 1, hydrocarbon mixtures 102 are selectedfor treatment to improve their utility and value. As shown in FIG. 1,the selected hydrocarbon mixtures 102 are then processed via a systemfor treating with cavitational energy 104 which results in an treatedhydrocarbon mixture 106 containing a higher content of distillable andmore valuable recoverable hydrocarbons. The lighter hydrocarbons maythen be recycled for further treatment at step 108 or recovered andseparated at step 110 from the heavier hydrocarbons using traditionaltechniques such as distillation. Although ultrasonic methods offer manybenefits in providing cavitational energy such as space, cost andefficiency, other methods of causing cavitation could be used in themethod of the present invention. These other methods include but are notlimited to propellers, impellers, venturi, electromagnetic waves, or anyother method sufficient to cause cavitation of the hydrocarbon mixture.

[0036] The hydrocarbon mixtures 102 may include a broad range ofhydrocarbon containing mixtures. Non-limiting examples of hydrocarbonmixtures which may benefit from application of the present invention arecrude oil, atmospheric tower refining bottoms, used motor oil, vacuumgas oils, refining residuums, fuel oils, vacuum tower bottoms, residualfuel oils, #6 fuel oils and mixtures of these hydrocarbons. Thesignificant amounts of heavy hydrocarbons in these mixtures decreasesboth their utility and value as commercial products. Traditionalprocesses for cracking these heavy hydrocarbon molecules requirecatalysts, usually heat, and suffer from the production of coke, foulingand pyrolysis. These hydrocarbon mixtures also often contain lighterhydrocarbons that do not distill during traditional separationsprocesses. Further, as mentioned earlier hydrocarbon mixtures andpetroleum products in particular contain a complex mixture of straightchain hydrocarbons, branched and cyclic hydrocarbons, aromatics,heterocyclic compounds and often include various non-carbon-containingconstituent groups. It is the presence of these heterocyclic andheteroatom compounds that often cause problems in traditional refiningprocesses such as fouling and discoloring and require hydrotreating oruse of additional processes to remove or reduce these effects.

[0037] One important aspect of the present invention is the absence ofthe requirement to add additional agents prior to treatment. However, itshould be noted that the presence of additives or an aqueous phase doesnot preclude use of the present invention. Those skilled in the art willrecognize that some feedstocks may require pretreatment to removetroublesome components, however the process has proven very versatileand no pretreatment is normally required. “Additives”, as used herein,is not intended to include components normally found in the subjectfeedstock or are added during prior processing or use. Treatment ofcrude oil in accordance with the present invention prior to thedistillation process will increase the yields of lighter hydrocarbonfractions and reduce the need for further processing such as cracking orother upgrading. Treatment of #6 fuel oil according to the method of thepresent invention produces both diesel boiling range fractions and theresidual is a high quality asphalt product.

[0038] The hydrocarbon mixture does not require heating for practice ofthe present invention and may even be practiced at ambient temperaturesor below. Although not required for practice of the present invention,the mixture can be heated to allow flow to occur. Frequently the mixturewill be pumped through a continuous system which requires a degree offlowability in the feedstock. Temperatures below about 300° F. typicallyprovide the desired flowability and temperatures less than about 20° F.above the pour point of the fluid should suffice for most applicationsof the present invention depending on other factors, discussed below,which may necessitate heating between about 300° F. and less than 500°F.

[0039] Another advantage of the present invention is that, becauseultrasonic cavitation equipment is significantly less expensive thanthermal or catalytic cracking equipment, processing of small volumestreams of hydrocarbon mixtures is economically feasible. Anotheradvantage of the invention is that the method produces no substantialenvironmental emissions or off gases. Further the method is a totallyself-contained process which may be easily moved to different locationsand occupies minimal space. Another advantage of the present inventionis that the method can be performed without requiring the formation ofemulsions either before or during the process of exposing thehydrocarbon mixture to cavitational energy.

[0040] Referring again to FIG. 1, the method steps in accordance withthe present invention begins by selecting 102 an appropriate hydrocarbonmixture for treatment. Typically, the process of the present inventionis applied to petroleum or hydrocarbon mixtures having a substantialconcentration of heavy hydrocarbons. Once the hydrocarbon mixture isselected, processing continues to the cavitational energy treatment step104. At this step, the hydrocarbon mixture is treated by applyingcavitational energy wherein the hydrocarbon mixture is directly exposedto cavitational energy. The preferred system for applying cavitationalenergy is described in greater detail below and one embodiment isdescribed hereinafter. When using ultrasonic cavitational energysources, it is desirable that the sound waves cycle at a rate sufficientto induce cavitation and implosion of the cavitation cavities in thehydrocarbon mixture and cause cracking of at least a portion of thehydrocarbons in the hydrocarbon mixture. Most often, the desire will beto crack the heavy hydrocarbons within the mixture to produce lightermore valuable hydrocarbon fractions. Ultrasonic cavitation tends tocrack the largest molecules first at the center of the molecule. Thisadvantageously reduces the amount of off-gases produced. The mixture issubjected to any frequency which is functional to obtain the desireddegree of cracking is acceptable for practice of the present invention.Sound waves having a frequency of about 5 kHz to about 500 kHz areuseful. However, frequencies from about 40 kHz to about 100 kHz areparticularly beneficial to cracking the carbon-carbon bond. In additionto these frequencies other variables will affect the occurrence ofcracking within the mixture such as increased power, exposure,amplitude, dwell-time, pressure and temperature.

[0041] The exposure time varies and is a function of the flow rate ofthe hydrocarbon mixture past the ultrasonic energy source, e.g., anultrasonic horn 306. Exposure is based on the desired degree of crackingand the properties of the feedstock. Exposure up to 500 W/cm² may benecessary to achieve the desired results. Further, exposure in the rangeof less than 500 W/cm² may work in combination with increasedtemperatures, pressures or dwell-time. Increasing the temperature of thehydrocarbon mixture between about 300° F. and less than 500° F. will aidin cracking of the mixture. Further, depending on the feedstock,pressures up to about 150 psi may be used. Other ultrasonic energysources may be used in accordance with the present invention such asmagnetorestrictive alloys, such as terfenol, or any other ultrasonicgenerators known to those skilled in the art. As mentioned earlier,other sources may produce the energy needed to produce cavitation withinthe hydrocarbon mixture. These cavitational energy sources include notonly ultrasonic horns and probes, but also propellers, impellers,venturi, electromagnetic waves and combinations of these sources.

[0042] In one embodiment of the present invention an ultrasonic horn isused as the cavitational energy source and the hydrocarbon mixture isdirected past the ultrasonic horn in a continuous process. Anotherimportant factor is the dwell-time, which may be increased to assist incracking of hydrocarbons in the mixture. The hydrocarbon mixture isprovided at a flow rate which depends on the quality and viscosity ofthe feedstock but may vary from about 1 to about 20 gallons per minutewhile a flow rate of about 1 to about 5 gallons per minute for a 1.5″ultrasonic horn are expected to yield good results. Further discussionof the flow past the ultrasonic energy source is provided in more detailbelow in relation to the “cup-shaped” flow tube.

[0043] The hydrocarbon mixture may be recycled through the cavitationaltreatment step as shown in step 108. The treated hydrocarbon mixture canbe tested at this point and recycled until the desired characteristicsare achieved. In order to obtain the desired degree of cracking severalpasses through the treatment step may be necessary. Alternatively,instead of continuously feeding a hydrocarbon mixture past an ultrasonichorn, a fixed amount of hydrocarbon mixture may be placed in a containeralong with ultrasonic energy inducing probes in a batch process. A batchtreatment according to this method would be particularly suited formixtures containing highly viscous hydrocarbons, residuums or heavywaxes but is less efficient than continuous flow processing.

[0044] The chemical effects of ultrasound are to enhance reaction ratesbecause of the formation of highly reactive radical species formedduring cavitation and the cleavage of covalent bonds. The scission ofcovalent bonds may cleave carbon-carbon bonds and/or bonds betweenheteroatoms and their neighbors. Additionally, the method of the presentinvention affects a reduction in van der Waals, polar attractive forces,hydrogen bonding and other attractive forces as a result of bothphysical and/or chemical changes.

[0045] While various methods of generating sound waves are known in theart, such as a sonic transducer with a magnetorestrictive alloy, thecurrently preferred method uses ultrasonic horns containingpiezo-electric crystals as the ultrasonic energy source 206, shown inFIG. 2. The hydrocarbon mixture is delivered to the ultrasonic energysource using any number of flow cell 204 configurations which define acontainment space and direct the flow of fluid for exposure to theultrasonic energy. A particularly effective flow cell for delivering thehydrocarbon mixture to the ultrasonic energy source is shown in FIG. 3.A “U” or cup-shaped flow tube 304 is placed to direct the flow offeedstock approaching the ultrasonic horns 206. The cup-shaped flowtube, due to its reduced diameter and “U” shape, enhances theeffectiveness of the system. It is thought that this improvedperformance is the result of increasing the velocity of the feedstockresulting in turbulent, rather than laminar flow, as the feedstockapproaches the ultrasonic horns. Several variables seem to affect theefficiency of the process and include the gap 308 between the flow tubeand the ultrasonic energy source, and the cupped walls on the flow tube.Tests performed using a flow tube without the cupped walls showed areduced effect on the distillation of the treated hydrocarbon mixture.Further, the gap should be adjusted to that which is functional toobtain the desired results. A narrow gap produces undesirable emulsionswhile a slightly larger gap will affect the desired results and requiresminimal experimentation to determine. For example, a configurationhaving a gap of ⅜″, an inlet diameter of ⅜″, and an ultrasonic horndiameter of 1.5″ is one operable configuration. However, a gap of about¼″ should assist in obtaining cracking and maybe a strong factor inintensifying the ultrasonic cavitation conditions among the otherfactors of temperature, pressure, exposure power and dwell-time. Theresulting turbulent flow and high pressures cause more of the feedstockto come into close contact with the ultrasonic horns resulting inincreased cavitation of the feedstock. The flow tube also directs thefeedstock across the full diameter of the ultrasonic horn and increasesthe exposure of the fluid to cavitational energy. The cup-shaped flowtube 304, as used in one embodiment of the present invention,advantageously and unexpectedly increases the cavitation of thehydrocarbon mixtures used as feedstock thereby increasing theeffectiveness of the process. Further, under laminar flow conditionswithout a cup-shaped flow tube increasing the flow rate of a sample ofused motor oil from 3 to 5 gpm resulted in poorer distillation results.However, the addition of the cup-shaped flow tube resulted in similardistillation results at 5 gpm as the 3 gpm tests without the flow tube.Thus, the cupped walls of the flow tube provide more favorableconditions for separating the various hydrocarbon fractions thanwithout.

[0046] A cup-shape flow tube which is effective in providing thediscussed results is a commercially available product available as ahigh pressure process cell assembly and is available in a range ofsizes. Using the 1.5″ flow tube and the above configuration produces anexposure of between about 40 W/cm² and 100 W/cm² when using a 1000 Wenergy supply. Increasing the exposure to less than 500 W/cm² may benecessary to achieve cracking in some feedstocks. Other flow tubes ordelivery systems directing flow toward the cavitational energy sourcewherein the flow is provided in the turbulent flow regime will alsoimprove the effectiveness of the cavitational energy treatment. Suchtubes and systems include also introducing obstructions or any change indiameter or flow-direction which would cause increased turbulent flowand mixing of the delivered feedstock.

[0047] Clearly, the optimal flow rate past the ultrasonic horns willdepend on a variety of factors such as feedstock viscosity, temperature,pressure, composition and flow tube characteristics delivering feedstockpast the ultrasonic horns. Feedstocks containing highly viscouscomponents will require lower flow rates or repeated exposure tocavitational energy.

[0048] Heavy hydrocarbon products of various processes such asatmospheric tower bottoms, residuums, asphalts and #6 fuel oil containsignificant amounts of heavy hydrocarbons, i.e. above the diesel fuelrange, which significantly impair their use and value. The highpressures and high temperatures from ultrasonic cavitation result incracking, which splits carbon-carbon (C—C) bonds of large hydrocarbonmolecules found in heavy hydrocarbon mixtures. Preferably, a portion ofthe heavy hydrocarbon molecules are split into lighter hydrocarbonfractions typically found in the diesel fuel range or lighter. It isknown that ultrasonic cavitation of water produces an H⁺ ion and an OH⁻ion. In the present invention, the presence of water during cavitationprovides a free hydroxyl radical to facilitate the cracking of thehydrocarbon molecule, and the H⁺ ion provides hydrogenation of the newlydivided hydrocarbon molecule and further improves its utility and helpsto avoid polymerization, alkylation, or other undesirable sidereactions. Further, the presence of heterocyclic and heteroatomhydrocarbon compounds, aromatics, trace elements and hydrocarbons havingnon-carbon constituent groups result in various reactions which improvethe properties of the treated hydrocarbon mixture. The treated mixturemay be stored or shipped without recovering or separating the varioushydrocarbon fractions and the later performed separation exhibitsessentially the same improvements in distillation yields as separationsperformed immediately after treatment with cavitational energy.

[0049] Referring again to FIG. 1, after the hydrocarbon mixture istreated by the cavitational energy in step 104, processing continues tostep 108 wherein the system determines whether the treatment iscomplete. For efficient processing, the hydrocarbon mixture should reacha predefined fractionation value. If at step 108 the predefinedthreshold has not been reached, processing returns to step 104 fortreatment with additional cavitational energy. If step 108 determinesthat the predefined threshold, such as fractionation value, has beenreached, processing continues to step 110. Most often a single passthrough the system is sufficient if the optimal conditions are chosen asdiscussed previously.

C. Example

[0050] Experimental Testing Procedures

[0051] The following test equipment was used: sonochemical horn (20kHz), sonochemical power supply (1000 W), process cell and ASTM D-86Atmospheric Distillation Test Apparatus. All percents shown are byvolume unless otherwise indicated.

[0052] A 100 ml sample of vacuum tower bottoms was tested for initialASTM D-86 Atmospheric Distillation values as shown in Table 3. A gallonof the vacuum tower bottoms at 300° F. was then placed in a continuousflow test bed where cavitation was then introduced by the ultrasonichorn into the sample using a flow configuration similar to that shown inFIG. 3, wherein the gap was ¼″. The cavitation was performed at apressure of 150 psi and provided at a rate of 1 gpm. The sample was thenre-tested for ASTM D-86 Atmospheric Distillation results which are shownin Table 3. TABLE 3 ASTM D-86 Atmospheric Distillation Results (° F.) %Recovered Before cavitation After cavitation Initial boiling point 635250  5% 670 @ 3% 325 10% 450 20% 550 30% 600 40% 620 50% 640 60% 660

[0053] Again, these results show a very significant increase in theyield of fractions boiling under 660° F. The treatment resulted in over55% increase in yield at about 660° F. Remember that the startingmaterial was vacuum tower bottoms and such improvement represents adramatic increase in diesel boiling range products having a greatervalue than the original. Practice of the present invention thereforeprovides for an increase in the number of smaller molecules and offersthe industry a new tool to maximize the yield of valuable hydrocarbonfractions.

[0054] D. System for Applying Ultrasonic Energy to Hydrocarbon Mixtures

[0055] A system of the present invention for applying ultrasonic energyto hydrocarbon mixtures and generating a treated hydrocarbon producthaving more distillable lighter hydrocarbons is shown in FIG. 2. In theembodiment shown in FIG. 2, the system for applying ultrasonic energyshown is a continuous feed system. The hydrocarbon mixture 202 iscontinuously fed through an incoming feed line 208 which is operativelyconnected to one or more ultrasonic sub-systems 212. The number ofsub-systems will depend on the desired capacity and may be arranged inseries or parallel based on basic process design principles for eitherprocessing or reliability factors. Although a plurality of ultrasonicsub-systems are shown in FIG. 2 only a single ultrasonic sub-system islabeled for convenience. Once treatment is complete, the treatedhydrocarbon mixture, or the fuel having a higher distillable hydrocarboncontent, is removed from the ultrasonic sub-system(s) 212 of the systemthrough a processed product return line 210.

[0056] A sample ultrasonic sub-system 212 is shown in FIG. 3. In thisparticular embodiment, the hydrocarbon mixture enters the flow cell 204which defines a containment space directing the flow of the hydrocarbonmixture. The ultrasonic sub-system applies ultrasonic energy to thehydrocarbon mixture by using an ultrasonic energy source 206. Oneembodiment of the flow cell 204 is the “U” or cup-shaped flow tube 304depicted in FIG. 3 and is particularly effective in delivering thehydrocarbon mixture to the ultrasonic horn although other flow cells andconfigurations would suffice for practice of the present invention. Thegap 308 between the ultrasonic energy source and the flow tube 304 is anexperimentally determined distance and may depend on a variety offactors. For the configuration shown where the flow tube inlet is ⅜″diameter and the ultrasonic energy source is ¾″ diameter, a gap of ¼″provides adequate results. Therefore, the appropriate configurationsrequire some minor experimentation based on the temperature, pressure,flow rates, exposure power and frequency to determine and are wellwithin the capacity of those skilled in the art.

[0057] The manner in which the flow is directed past the ultrasonic horndirectly affects the efficiency of the treatment process and care shouldbe taken to provide for maximum exposure of the fluid across the surfaceof the ultrasonic horn. The treated hydrocarbon mixture exits theultrasonic sub-system 212 via the processed product return line 210. Thetreated hydrocarbon mixture may then be stored or processed further viadistillation or other refining processes.

[0058] The system, including the ultrasonic sub-systems, are describedin these terms for convenience purposes only. In addition, thecomponents of the system described herein are commercially availablewherein it is well known by a person of ordinary skill in the relevantart to design, implement, and operate such a system in order to performthe method of separating various hydrocarbon fractions from ahydrocarbon mixture according to the present invention.

Conclusion

[0059] While various embodiments of the present invention have beendescribed above, it should be understood that they have been presentedby way of example only, and not limitation. It will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined in the specification and the appended claims. Thus,the breadth and scope of the present invention should not be limited byany of the above-described exemplary embodiments, but should be definedin accordance with the specification and any equivalents.

What is claimed is:
 1. A method of upgrading a hydrocarbon mixture,comprising the steps of: (a) providing a hydrocarbon mixture to beupgraded; and (b) treating the hydrocarbon mixture with cavitationalenergy, wherein the cavitational energy induces cavitation in thehydrocarbon mixture sufficient to cause cracking of a portion of thehydrocarbons within the hydrocarbon mixture to produce a treatedhydrocarbon mixture, wherein the treated hydrocarbon mixture comprisesat least two hydrocarbon fractions.
 2. The method of claim 1, whereinthe cavitational energy is provided using a cavitational energy sourceselected from the group consisting of ultrasonic, electromagnetic,propeller, impeller, venturi and combinations thereof.
 3. The method ofclaim 2, wherein the cavitational energy source is an ultrasonic source.4. The method of claim 3, wherein the ultrasonic source comprises one ormore ultrasonic horns.
 5. The method of claim 3, wherein thecavitational energy has a frequency of about 5 kHz to about 500 kHz. 6.The method of claim 5, wherein the cavitational energy has a frequencyof about 40 kHz to about 100 kHz.
 7. The method of claim 3, wherein thecavitational energy is less than 500 W/cm².
 8. The method of claim 7,wherein the cavitational energy is less than about 375 W/cm².
 9. Themethod of claim 3, wherein the hydrocarbon mixture is provided at apressure of about 150 psi.
 10. The method of claim 1, wherein thehydrocarbon mixture is selected from the group consisting of crude oil,atmospheric tower refining bottoms, used motor oil, vacuum gas oils,refining residuums, cat cracker bottoms, fuel oil, vacuum tower bottoms,residual fuel oils and mixtures thereof.
 11. The method of claim 1,wherein the hydrocarbon mixture further comprises organic componentscontaining heteroatoms selected from the group consisting of nitrogen,sulfur, oxygen and mixtures thereof.
 12. The method of claim 1, whereinthe hydrocarbon mixture comprises predominantly hydrocarbons having aboiling point greater than that of diesel.
 13. The method of claim 1,wherein the hydrocarbon mixture is treated at a temperature betweenabout 300° F. and less than 500° F.
 14. The method of claim 1, whereinthe hydrocarbon mixture having a predetermined pour point is treated ata temperature less than about 20° F. over the pour point of thehydrocarbon mixture.
 15. The method of claim 1, wherein the hydrocarbonmixture is treated in the absence of substantial amounts of an aqueousphase or additives.
 16. The method of claim 1, further comprising thestep of separating the at least two hydrocarbon fractions from thetreated hydrocarbon mixture into separate fractions.
 17. The method ofclaim 16, wherein the step of separating is accomplished viadistillation.
 18. The method of claim 1, further comprising subjectingthe treated hydrocarbon mixture to step (b) multiple times until thetreated hydrocarbon mixture exhibits a predetermined fractionationvalue.
 19. A treated hydrocarbon mixture produced by the method of claim1, wherein the treated hydrocarbon mixture has a higher distillablehydrocarbon content than the original hydrocarbon mixture.
 20. A methodof upgrading a hydrocarbon mixture, comprising the steps of: (a)providing a hydrocarbon mixture in the absence of substantial amounts ofan aqueous phase or additives; (b) treating the hydrocarbon mixture withultrasonic energy, wherein the ultrasonic energy induces cavitation inthe hydrocarbon mixture sufficient to crack a portion of thehydrocarbons within the hydrocarbon mixture to produce a treatedhydrocarbon mixture, wherein the treated hydrocarbon mixture comprisesat least two hydrocarbon fractions; and (c) separating the at least twohydrocarbon fractions from the treated hydrocarbon mixture into separatefractions.
 21. A method of upgrading a hydrocarbon mixture, comprisingthe steps of: (a) providing a hydrocarbon mixture in the absence ofsubstantial amounts of an aqueous phase or additives, wherein thehydrocarbon mixture has a predetermined pour point; (b) treating thehydrocarbon mixture with ultrasonic energy at a temperature from thepour point of the hydrocarbon mixture to about 20° F. over the pourpoint, wherein the ultrasonic energy induces cavitation in thehydrocarbon mixture sufficient to crack a portion of the hydrocarbonswithin the hydrocarbon mixture to produce a treated hydrocarbon mixture,wherein the treated hydrocarbon mixture comprises at least twohydrocarbon fractions; and (c) separating the at least two hydrocarbonfractions from the treated hydrocarbon mixture into separate fractions.22. A method of upgrading a hydrocarbon mixture, comprising the stepsof: (a) providing a hydrocarbon mixture; (b) providing a means fordelivering the hydrocarbon mixture to a source of ultrasonic energyusing a cup-shaped flow tube; (c) treating the hydrocarbon mixture withultrasonic energy, wherein the ultrasonic energy induces cavitation inthe hydrocarbon mixture sufficient to crack a portion of thehydrocarbons within the hydrocarbon mixture to produce a treatedhydrocarbon mixture, wherein the treated hydrocarbon mixture comprisesat least two hydrocarbon fractions.
 23. A continuous self-containedultrasonic treatment system for upgrading hydrocarbon mixturescomprising: (a) a containment space for containing the hydrocarbonmixture; (b) an inlet line operatively connected to the containmentspace; (c) at least one ultrasonic energy source for emitting ultrasonicenergy positioned such that the ultrasonic energy passes through thecontainment space; (d) an outlet line operatively connected to thecontainment space to allow for withdrawal of the hydrocarbon mixture;and (e) a cup-shaped flow tube operatively connected to the containmentspace and oriented to direct flow of the hydrocarbon mixture toward theultrasonic energy source.
 24. A method of upgrading a hydrocarbonmixture, comprising the steps of: (a) providing a hydrocarbon mixturehaving a predetermined pour point, wherein the hydrocarbon mixture issubstantially free of an aqueous phase and additives and is at atemperature less than 20° F. over the pour point; (c) directing thehydrocarbon mixture toward an ultrasonic energy source using acup-shaped flow tube; (b) treating the hydrocarbon mixture withultrasonic energy emitted from the ultrasonic energy source, wherein theultrasonic energy has sufficient energy to crack a portion of thehydrocarbons within the hydrocarbon mixture to produce a treatedhydrocarbon mixture, wherein the treated hydrocarbon mixture comprisesat least two hydrocarbon fractions; and (c) recovering the at least twohydrocarbon fractions from the treated hydrocarbon mixture.